How does a twin spark single ignition coil work?
If you search, you can find the patent description, which explains it. http://www.freepatentsonline.com/7332991.html Here is the summary abstract … “A twin spark ignition apparatus having two high-voltage (HV) outputs incorporates features for balancing load capacitance on each HV output. The ignition apparatus provides a first high-voltage (HV) connection configured for direct mounting on a first spark plug, and a second HV connection for coupling to a second spark plug by way of an HV cable. The HV cable adds capacitance at the second HV output, as compared to a direct mount. The secondary winding is shifted by a predetermined distance, relative to the primary winding, in direction toward the direct mount end of the ignition apparatus. The shifting reduces the internal load capacitance at the second end (top), so that when the capacitance added by the HV cable is considered, the respective load capacitances are balanced.